Optical sensors are a necessary and ubiquitous part of the cameras used in the field of digital camera surveillance. Optical sensors differ somewhat in their exact implementation, but a common feature is to use the photoelectric effect to measure light incident to a surface of the optical sensor. The photoelectric effect is a phenomenon wherein electrons of a metal absorb the energy of photons which strike the surface of the metal. Therefore, the optical sensors used in the field of digital camera surveillance can be said to respond to the energy of incident light. A problem arises when the optical sensor also absorbs thermal energy through heat. Such heat may, for example, originate from the electric circuitry used to control and read out the photoelectric information from the optical sensor. The electrons of the optical sensor may absorb such thermal energy and give a signal as though they had measured a photon. This may lead to unwanted saturation and noise of the produced image, making it less clear, meaning that details of the image may be lost. This is typically unwanted in most cases where an image is captured. It is, for example, typically unwanted in the field of surveillance, where details of an image may be of critical or even fatal importance. Therefore, digital cameras are typically designed to divert the heat generated by the processors in the camera. The heat may be conducted to a portion of the camera which has contact with air to which the heat may be dissipated through convection, such as cooling flanges or simply a chassis of the camera. The heat being conducted through parts of the camera may cause said parts to expand or deform in other ways, creating stresses and strains in the camera. This means that the camera must be constructed with these stresses and strains in mind, leading to solutions which may be expensive and difficult to design the camera around. Moreover, expansion or deformation may displace the lens of the camera with regards to the image sensor, causing loss of focus and blurry images as a result. There are numerous prior art attempts to address the above discussed problems.
U.S. Pat. No. 9,407,802 discusses that deterioration in image forming characteristics may be caused by thermal expansion/thermal contraction of adhesive which is used to fix the image. The thermal expansion changes the position of the image sensor which is displaced from the original preferable position, causing the deterioration in image-forming characteristics. In this document this is addressed by providing additional movement suppressing members. However, it may be noted that it does not really address the issue of dissipating heat from the image sensor.
Therefore, there is still room for improvements when it comes to designing a camera which has a reduced risk of loss of focus as a result of thermal expansion, and which still is easy to manufacture and assemble.